The present invention relates to a trigger event detection apparatus of the type that, for example, receives, when in use, an input signal and analyses the input signal in order to detect a trigger event. The present invention also relates to a method of detecting a trigger event of the type that, for example, receives an input signal and analyses the input signal in order to detect the trigger event.
In the field of Radio Resource Management, a Radio Frequency (RF) signal is known to possess a number of characteristics, for example: power, duration, modulation, and space-time coding format. One or more of the characteristics are dynamic and so are changeable. Radio Resource Management, generally speaking, is the practice of optimisation of performance of an RF system by varying one or more of the characteristics.
In order to understand whether the RF system is responding correctly and effectively to changes in an RF environment in which the RF system operates, it is necessary to trigger a measurement instrument on a channel event to which a change in the one or more characteristics responds. A number of causes of the channel event exist, for example fading, interference and/or an error in the RF system. In this respect, certain events are infrequent or sporadic and so it is not possible always to predict when such events will occur and/or the exact nature of such events.
It is known to trigger the measurement instrument based upon RF level and/or frequency criteria, and such criteria allows some signals to be identified for analysis. However, such criteria are not always able to identify a difference in signal type where, for example, modulation type is a distinguishing factor between wanted and unwanted signals to be captured for analysis. For example, a Wireless Local Area Network (WLAN) Access Point, operating in accordance with a communications standard, such as, the Institute of Electronic and Electrical Engineers (IEEE) 802.11g standard, can switch between Direct Sequence Spread-Spectrum (DSSS) modulation and Orthogonal Frequency Division Multiplexing (OFDM) modulation on a same frequency depending upon performance of an RF channel and network operation. Also, the WLAN Access Point uses different types of burst in order to achieve performance of certain network activities. Changes in such characteristics (and others) are not predictable, and not readily detectable for triggering purposes, using existing techniques described above.
Demodulation of an RF signal can be used to provide triggers, but use of demodulation is technology specific and also carries a processing overhead and time penalty when implemented. Furthermore, use of demodulation may not work if the RF signal cannot be demodulated due to one or more errors in the way the RF signal was generated.